OK, true confession first: I know nothing about the subject treated in Introduction to Maximum Principles and Symmetry in Elliptic Problems. But how could I resist? The introduction, speaking of the course at the University of Bath that led to this book, says, after describing a pamphlet that specified the goal of the course:

Naturally, the pamphlet did not state how this goal was to be reached in twenty lectures to students who could not be assumed to have any experience whatever of partial differential equations. Nor were detailed suggestions issued to me when, in the autumn of 1988, I joined the University of Bath and was ordered to give these lectures...

The author goes on to say that "the word Introduction in the title of the book is no gloss." The book tries to make good on the promise to lead the student quickly into the theory with minimal prerequisites by including a lot of background material in five appendices. The writing is lively and has a touch of humor. While it's certainly not easy, it strives to be friendly and to help the reader along. All in all, this seems a worthwhile introduction to some interesting material.